Heretofore, more or less standard exhaust valves have been utilized to remove air from the sand magazine area of mold and core blowing machines and some equipment could blow, cure and strip the core from the core box without moving the box horizontally but all such equipment had to raise and lower from the blow plate. This function could not be accomplished after the core box was raised and blown until all of the air was exhausted from the sand magazine through one or more of the exhaust valves. The exhaust valves consistently were provided with small inlet and outlet ports and as a consequence generated considerable noise because adequate means for silencing or muffling the exhaust could not be provided. The small porting resulted in the use of relatively small mufflers which were ineffective because of their small size and which also lengthened the time required to remove the air from the area of the sand magazine. This, of course, had the effect of lowering the overall production output from the machine. Manufacturers, of course, desire to reduce the noise in their foundry operations for the benefit of the employees in these areas and to improve relations with employee unions but they want to accomplish this without adversely affecting their total production and without reducing their profit potential. The relatively small effective size of prior exhaust valves resulting from the small size porting used caused an undue amount of downtime for cleaning the valves.